style: enforce clippy::disallowed_macros for direct log use

Add clippy.toml with disallowed-macros configuration
that prevents direct use of log::error, log::warn, and
log::info. Enable the lint as deny in workspace clippy
config.

The rate-limited macro helper uses
allow(clippy::disallowed_macros) internally since it
must call the underlying log macros. The
log_dev_preview_warning function is also allowed since
it is not guest-triggerable.

Non-vmm crates (firecracker, cpu-template-helper,
log-instrument examples) are allowed since they do not
have access to the rate-limited macros and their log
calls are not guest-triggerable.

Signed-off-by: Nikita Kalyazin <kalyazin@amazon.com>

Author: kalyazin

Cargo.toml

@@ -20,6 +20,7 @@ missing_debug_implementations = "warn"
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(kani)'] }
 
 [workspace.lints.clippy]
+disallowed_macros = "deny"
 ptr_as_ptr = "warn"
 undocumented_unsafe_blocks = "warn"
 cast_possible_truncation = "warn"

clippy.toml

@@ -0,0 +1,5 @@
+disallowed-macros = [
+    { path = "log::error", reason = "use error_rate_limited! to prevent excessive host log output" },
+    { path = "log::warn", reason = "use warn_rate_limited! to prevent excessive host log output" },
+    { path = "log::info", reason = "use info_rate_limited! to prevent excessive host log output" },
+]

src/cpu-template-helper/src/main.rs

@@ -1,6 +1,8 @@
 // Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+#![allow(clippy::disallowed_macros)]
+
 use std::fs::{read_to_string, write};
 use std::path::PathBuf;
 

src/cpu-template-helper/src/template/dump/aarch64.rs

@@ -1,5 +1,6 @@
 // Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
+#![allow(clippy::disallowed_macros)]
 
 use vmm::arch::aarch64::regs::{PC, RegSize, SYS_CNTPCT_EL0, SYS_CNTV_CVAL_EL0};
 use vmm::cpu_config::aarch64::custom_cpu_template::RegisterModifier;

src/firecracker/src/api_server/mod.rs

@@ -1,5 +1,6 @@
 // Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
+#![allow(clippy::disallowed_macros)]
 
 //! Implements the interface for intercepting API requests, forwarding them to the VMM
 //! and responding to the user.

src/firecracker/src/api_server/parsed_request.rs

@@ -1,5 +1,6 @@
 // Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
+#![allow(clippy::disallowed_macros)]
 
 use std::fmt::Debug;
 

src/firecracker/src/api_server_adapter.rs

@@ -1,5 +1,6 @@
 // Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
+#![allow(clippy::disallowed_macros)]
 
 use std::os::unix::io::AsRawFd;
 use std::path::PathBuf;

src/firecracker/src/main.rs

@@ -1,6 +1,10 @@
 // Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+// The firecracker binary uses direct log macros for startup, API, and
+// shutdown paths that are not guest-triggerable.
+#![allow(clippy::disallowed_macros)]
+
 #[cfg(all(feature = "fuzzing", not(debug_assertions)))]
 compile_error!(
     "The `fuzzing` feature must not be used in release builds. \

src/firecracker/src/metrics.rs

@@ -1,5 +1,6 @@
 // Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
+#![allow(clippy::disallowed_macros)]
 
 use std::os::unix::io::AsRawFd;
 use std::time::Duration;

src/log-instrument/examples/five.rs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #![warn(clippy::pedantic)]
+#![allow(clippy::disallowed_macros)]
 
 use log::{LevelFilter, debug, info, warn};